This sounds a lot like the fixed timeline theory. If you were to go back in time and kill Adolf Hitler as a baby in order to prevent WWII and replace him with another baby so that the family doesn't notice. That baby will in turn grow up to become Adolf Hitler himself.

well he did win the man of the year award in time magazine twice before ww2 started sooo clearly he was doing a good job before he turned on everyone. He's always frowned upon but you have to hand it to him, he was a fucking genius. He almost conquered all of Europe, he was very charismatic and he was a natural leader. His only mistake was following into Napoleans footsteps and freezing his men to death in Russia

Hitler was an incredibly charismatic and very capable leader, but people should stop attributing all that success to him. He was also surrounded by incredibly competent people, world leaders in their respective fields, and it was his ability to unite them that was his most useful trait.

Otherwise, he fucked up quite a lot. Besides, he NEEDED to invade Russia at some point, and what better time to do it than after a defeat at Britain, when his people needed a morale boost, and Stalin had just purged his own military of hundreds of officers?